In cutting tools of the above-defined kind, usually the flank of the flute has a smooth surface. Thus the tool has a maximal contact surface with the chips that are heated during the cutting process, and as a result is constantly being heated to an increasing degree. In addition the large contact surface cause greater wear which affects at least the secondary cutting edges The life of the tool is shortened and the quality of the workpiece surface produced by machining is lowered. Hence the efficiency of heavy-duty tools of hard metal, ceramic material, and of extra-hard cutting materials is reduced.
All this disadvantageously affects standard shank drills as well as end-mill cutters and like tools, and is particularly noticeable in the case of drill-milling cutters, i.e. in tools such as have been used lately for drilling and milling operations in order to avoid tool replacements. A primary field of application is the processing of so-called sandwich or composite materials of the type used in the electronic field, particularly for printed circuit boards.